基于okhttp和RxJava封装的自动重连的WebSocket

*本篇文章已授权微信公众号 guolin_blog （郭霖）独家发布

一 . 概述

1. RxWebSocket是一个基于okhttp和RxJava(RxJava1和RxJava2都支持)封装的WebSocket客户端,此库的核心特点是 除了手动关闭WebSocket(就是RxJava取消订阅),WebSocket在异常关闭的时候(onFailure,发生异常,如WebSocketException等等),会自动重连,永不断连.其次,对WebSocket做的缓存处理,同一个URL,共享一个WebSocket.

2. 由于是基于RxJava封装,所以带来了无限可能,可以和RxBinding,Rxlifecycle一起使用,方便对WebSocket的管理.

项目地址: 欢迎star

• https://github.com/dhhAndroid/RxWebSocket

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  效果图

  

重连

项目已经上传Jcenter,依赖方法:

//本项目compile 'com.dhh:websocket:1.3.0'//由于项目是基于okhttp,RxJava,RxAndroid编写,所以还需加入如下依赖.//okhttp,RxJava,RxAndroidcompile 'com.squareup.okhttp3:okhttp:3.9.0'compile 'io.reactivex:rxjava:1.3.1'compile 'io.reactivex:rxandroid:1.2.1'

二 . 使用方法

0. 初始化,可以也忽略直接使用.

如果你想使用自己的okhttpClient:

        OkHttpClient yourClient = new OkHttpClient();        RxWebSocketUtil.getInstance().setClient(yourClient);

是否打印日志:

RxWebSocketUtil.getInstance().setShowLog(BuildConfig.DEBUG);

1.获取一个WebSocket,接收消息,多种方式:

RxWebSocketUtil.getInstance().getWebSocketInfo(url)                        .subscribe(new Action1<WebSocketInfo>() {                            @Override                            public void call(WebSocketInfo webSocketInfo) {                                mWebSocket = webSocketInfo.getWebSocket();                                Log.d("MainActivity", webSocketInfo.getString());                                Log.d("MainActivity", "ByteString:" + webSocketInfo.getByteString());                            }                        });mWebSocket.send("hello word");        //get StringMsg        RxWebSocketUtil.getInstance().getWebSocketString(url)                .subscribe(new Action1<String>() {                    @Override                    public void call(String s) {                    }                });        // get ByteString        RxWebSocketUtil.getInstance().getWebSocketByteString(url)                .subscribe(new Action1<ByteString>() {                    @Override                    public void call(ByteString byteString) {                    }                });        //get WebSocket        RxWebSocketUtil.getInstance().getWebSocket(url)                .subscribe(new Action1<WebSocket>() {                    @Override                    public void call(WebSocket webSocket) {                    }                });       // 带timeout的WebSocket,当在指定时间内没有收到消息,就重连WebSocket.为了适配小米平板.       //小米平板测试的时候,出现网络断连,不发送错误,导致不能重连        RxWebSocketUtil.getInstance().getWebSocketInfo(url,10, TimeUnit.SECONDS)                .subscribe(new Action1<WebSocketInfo>() {                    @Override                    public void call(WebSocketInfo webSocketInfo) {                    }                });       

2. 发送消息:

  //用WebSocket的引用直接发  mWebSocket.send("hello word");  //url 对应的WebSocket已经打开可以这样send,否则报错  RxWebSocketUtil.getInstance().send(url, "hello");  RxWebSocketUtil.getInstance().send(url, ByteString.EMPTY);  //异步发送,若WebSocket已经打开,直接发送,若没有打开,打开一个WebSocket发送完数据,直接关闭.  RxWebSocketUtil.getInstance().asyncSend(url, "hello");  RxWebSocketUtil.getInstance().asyncSend(url, ByteString.EMPTY);

3.关闭WebSocket

项目是依托RxJava实现的,所以关闭WebSocket的方法也就是在适当的时候注销 Observable,项目里的demo里,写了一个简单的lifecycle,将Observable生命绑定到Activity的onDestroy,自动注销.代码细节请看demo,因为内部实现了同一个URL的WebSocket共享机制,所以当外部所有持有这个URL的Observable都注销后,这个WebSocket连接就会自动关闭.请看原理解析部分.下面两种常用注销方法:

       //注意取消订阅,有多种方式,比如 rxlifecycle                        mSubscription = RxWebSocketUtil.getInstance().getWebSocketInfo(url)                                .subscribe(new Action1<WebSocketInfo>() {                                    @Override                                    public void call(WebSocketInfo webSocketInfo) {                                        mWebSocket = webSocketInfo.getWebSocket();                                        if (webSocketInfo.isOnOpen()) {                                            Log.d("MainActivity", " on WebSocket open");                                        } else {                                            String string = webSocketInfo.getString();                                            if (string != null) {                                                Log.d("MainActivity", string);                                                textview.setText(Html.fromHtml(string));                                            }                                            ByteString byteString = webSocketInfo.getByteString();                                            if (byteString != null) {                                                Log.d("MainActivity", "webSocketInfo.getByteString():" + byteString);                                            }                                        }                                    }                                });    //注销    if (mSubscription != null) {            mSubscription.unsubscribe();        }//lifecycle注销,详情看demo        RxWebSocketUtil.getInstance().getWebSocketString(url)                .compose(this.<String>bindOnActivityEvent(ActivityEvent.onDestory))                .subscribe(new Action1<String>() {                    @Override                    public void call(String s) {                    }                });

三. 原理解析

1. 首先需要将okhttp的WebSocket包装成Observable,由于需要将WebSocket,Stringmsg,ByteString等信息一同发送给观察者所以先构建一个WebSocketInfo类,将信息封装:

public class WebSocketInfo {    private WebSocket mWebSocket;    private String mString;    private ByteString mByteString;    private boolean onOpen;    //其他省略}

onOpen字段主要用来判断当前的这个WebSocketInfo是否是当WebSocket打开时发送的消息(onOpen),这时,Stringmsg和ByteString都是null.

2. 将WebSocketInfo包装成Observable发出:

    private final class WebSocketOnSubscribe implements Observable.OnSubscribe<WebSocketInfo> {        private String url;        private WebSocket webSocket;        private WebSocketInfo startInfo, stringInfo, byteStringInfo;        public WebSocketOnSubscribe(String url) {            this.url = url;            startInfo = new WebSocketInfo(true);            stringInfo = new WebSocketInfo();            byteStringInfo = new WebSocketInfo();        }        @Override        public void call(final Subscriber<? super WebSocketInfo> subscriber) {            if (webSocket != null) {                //降低重连频率                if (!"main".equals(Thread.currentThread().getName())) {                    SystemClock.sleep(2000);                }            }            initWebSocket(subscriber);        }        private void initWebSocket(final Subscriber<? super WebSocketInfo> subscriber) {            webSocket = client.newWebSocket(getRequest(url), new WebSocketListener() {                @Override                public void onOpen(final WebSocket webSocket, Response response) {                    if (showLog) {                        Log.d("RxWebSocketUtil", url + " --> onOpen");                    }                    webSocketMap.put(url, webSocket);                    AndroidSchedulers.mainThread().createWorker().schedule(new Action0() {                        @Override                        public void call() {                            if (!subscriber.isUnsubscribed()) {                                subscriber.onStart();                                startInfo.setWebSocket(webSocket);                                subscriber.onNext(startInfo);                            }                        }                    });                }                @Override                public void onMessage(WebSocket webSocket, String text) {                    if (!subscriber.isUnsubscribed()) {                        stringInfo.setWebSocket(webSocket);                        stringInfo.setString(text);                        subscriber.onNext(stringInfo);                    }                }                @Override                public void onMessage(WebSocket webSocket, ByteString bytes) {                    if (!subscriber.isUnsubscribed()) {                        byteStringInfo.setWebSocket(webSocket);                        byteStringInfo.setByteString(bytes);                        subscriber.onNext(byteStringInfo);                    }                }                @Override                public void onFailure(WebSocket webSocket, Throwable t, Response response) {                    if (showLog) {                        Log.e("RxWebSocketUtil", t.toString() + webSocket.request().url().uri().getPath());                    }                    if (!subscriber.isUnsubscribed()) {                        subscriber.onError(t);                    }                }                @Override                public void onClosing(WebSocket webSocket, int code, String reason) {                    webSocket.close(1000, null);                }                @Override                public void onClosed(WebSocket webSocket, int code, String reason) {                    if (showLog) {                        Log.d("RxWebSocketUtil", url + " --> onClosed:code= " + code);                    }                }            });            subscriber.add(new MainThreadSubscription() {                @Override                protected void onUnsubscribe() {                    webSocket.close(3000, "手动关闭");                }            });        }    }

实现一个WebSocketOnSubscribe 将WebSocket的回调转化成subscriber调用.发送给Observable下游.在onOpen时调用 subscriber.onStart(),并且发送一个onOpen的WebSocketInfo.在subscriber注销的时候关闭WebSocket.在call方法最上面有个SystemClock.sleep(2000),这个主要是为了降低在断连的时候的重连频率,将在下面讲到.

包装成Observable:

Observable.create(new WebSocketOnSubscribe(url))                    .subscribeOn(Schedulers.io())                    .observeOn(AndroidSchedulers.mainThread());

3. 实现自动重连:

Observable.create(new WebSocketOnSubscribe(url))                    //自动重连                    .timeout(timeout, timeUnit)                    .retry()                    .subscribeOn(Schedulers.io())                    .observeOn(AndroidSchedulers.mainThread());

RxJava retry操作符,很完美的实现了这个功能,当上游发出Throwable的时候,retry将错误吃掉,并重新调用 onSubscribe的call方法,也就是WebSocketOnSubscribe的call,就会重新初始化一个WebSocket连接,达到重连的目的,如果一直没有网络,这个retry的调用频率非常高,所以在call方法里面,当是重连的时候,就SystemClock.sleep(2000),休眠2秒,这样重连的频率就是2秒重连一次. 当然在retry上面还有一个timeout操作符.当subscriber.onNext()在指定时间间隔里没有调用,就发出一个timeoutException,让retry重连WebSocket.这个主要是为了适配部分国产机型,当WebSocket发生连接异常时,不会及时发出错误,如小米平板.在每次重连都会把原来的WebSocket关闭.

4. 实现同一个URL的WebSocket共享

Observable.create(new WebSocketOnSubscribe(url))                    //自动重连                    .timeout(timeout, timeUnit)                    .retry()                    //共享                    .doOnUnsubscribe(new Action0() {                        @Override                        public void call() {                            observableMap.remove(url);                            webSocketMap.remove(url);                            if (showLog) {                                Log.d("RxWebSocketUtil", "注销");                            }                        }                    })                    .doOnNext(new Action1<WebSocketInfo>() {                        @Override                        public void call(WebSocketInfo webSocketInfo) {                            if (webSocketInfo.isOnOpen()) {                                webSocketMap.put(url, webSocketInfo.getWebSocket());                            }                        }                    })                    .share()                    .subscribeOn(Schedulers.io())                    .observeOn(AndroidSchedulers.mainThread());

实现共享功能,主要是为了防止一个URL的WebSocket,建立多个连接,这个主要是由RxJava的share操作符实现,share操作符,使得一个Observable可以有多个subscriber,当有多个subscriber时,当所有的subscriber都取消订阅,这个Observable才会取消订阅. getWebSocketInfo()方法完整代码:

    public Observable<WebSocketInfo> getWebSocketInfo(final String url, final long timeout, final TimeUnit timeUnit) {        Observable<WebSocketInfo> observable = observableMap.get(url);        if (observable == null) {            observable = Observable.create(new WebSocketOnSubscribe(url))                    //自动重连                    .timeout(timeout, timeUnit)                    .retry()                    //共享                    .doOnUnsubscribe(new Action0() {                        @Override                        public void call() {                            observableMap.remove(url);                            webSocketMap.remove(url);                            if (showLog) {                                Log.d("RxWebSocketUtil", "注销");                            }                        }                    })                    .doOnNext(new Action1<WebSocketInfo>() {                        @Override                        public void call(WebSocketInfo webSocketInfo) {                            if (webSocketInfo.isOnOpen()) {                                webSocketMap.put(url, webSocketInfo.getWebSocket());                            }                        }                    })                    .share()                    .subscribeOn(Schedulers.io())                    .observeOn(AndroidSchedulers.mainThread());            observableMap.put(url, observable);        } else {            observable = Observable.merge(Observable.just(new WebSocketInfo(webSocketMap.get(url), true)), observable);        }        return observable;    }

doOnUnsubscribe作用:在Observable注销,即 WebSocket关闭时,移除map中的缓存的Observable和WebSocket.

doOnNext作用: 判断接收到的WebSocketInfo是否是WebSocket在onOpen的时候发的,然后将其缓存起来.作用就是:如果有一个相同的URL订阅Observable,就从缓存中取,这个时候我们应该把一个WebSocket的onOpen事件也发给这个订阅者:

//使用merge操作符,将onOpen事件发给订阅者observable = Observable.merge(Observable.just(new WebSocketInfo(webSocketMap.get(url), true)), observable);

这样的话,同一个URL的WebSocket,不管在什么地方什么时间订阅,都能收到一个onOpen事件,外部表现的就像一个新的WebSocket.

getWebSocketInfo方法的几种变体:

    /**     * default timeout: 30 days     * <p>     * 若忽略小米平板,请调用这个方法     * </p>     */    public Observable<WebSocketInfo> getWebSocketInfo(String url) {        return getWebSocketInfo(url, 30, TimeUnit.DAYS);    }    public Observable<String> getWebSocketString(String url) {        return getWebSocketInfo(url)                .map(new Func1<WebSocketInfo, String>() {                    @Override                    public String call(WebSocketInfo webSocketInfo) {                        return webSocketInfo.getString();                    }                })                .filter(new Func1<String, Boolean>() {                    @Override                    public Boolean call(String s) {                        return s != null;                    }                });    }    public Observable<ByteString> getWebSocketByteString(String url) {        return getWebSocketInfo(url)                .map(new Func1<WebSocketInfo, ByteString>() {                    @Override                    public ByteString call(WebSocketInfo webSocketInfo) {                        return webSocketInfo.getByteString();                    }                })                .filter(new Func1<ByteString, Boolean>() {                    @Override                    public Boolean call(ByteString byteString) {                        return byteString != null;                    }                });    }    public Observable<WebSocket> getWebSocket(String url) {        return getWebSocketInfo(url)                .map(new Func1<WebSocketInfo, WebSocket>() {                    @Override                    public WebSocket call(WebSocketInfo webSocketInfo) {                        return webSocketInfo.getWebSocket();                    }                });    }

5 . send信息到服务端

上面已经讲到WebSocketInfo包含了WebSocket,所以在订阅后,就可以拿到这个WebSocket引用就可以WebSocket.send发送消息到服务端.当然我们的RxWebSocketUtil已经将开启的WebSocket已经缓存.所以我们也可以这样发消息:

    /**     * 如果url的WebSocket已经打开,可以直接调用这个发送消息.     *     * @param url     * @param msg     */    public void send(String url, String msg) {        WebSocket webSocket = webSocketMap.get(url);        if (webSocket != null) {            webSocket.send(msg);        } else {            throw new IllegalStateException("The WebSokcet not open");        }    }    /**     * 如果url的WebSocket已经打开,可以直接调用这个发送消息.     *     * @param url     * @param byteString     */    public void send(String url, ByteString byteString) {        WebSocket webSocket = webSocketMap.get(url);        if (webSocket != null) {            webSocket.send(byteString);        } else {            throw new IllegalStateException("The WebSokcet not open");        }    }

当指定的URL的WebSocket没有打开会直接报错.

异步发送消息到服务端

    /**     * 不用关心url 的WebSocket是否打开,可以直接发送     *     * @param url     * @param msg     */    public void asyncSend(String url, final String msg) {        getWebSocket(url)                .first()                .subscribe(new Action1<WebSocket>() {                    @Override                    public void call(WebSocket webSocket) {                        webSocket.send(msg);                    }                });    }    /**     * 不用关心url 的WebSocket是否打开,可以直接发送     *     * @param url     * @param byteString     */    public void asyncSend(String url, final ByteString byteString) {        getWebSocket(url)                .first()                .subscribe(new Action1<WebSocket>() {                    @Override                    public void call(WebSocket webSocket) {                        webSocket.send(byteString);                    }                });    }

这两种发送方式,你不用关心URL的WebSocket是否打开,可以直接发送.实现思路也很简单,getWebSocket(url)会获取到Observable,或者是从缓存中取,或者是重新开启一个WebSocket,但你都不需要关心,经过first操作符后,如果是从缓存取的Observable,就注销的当前的Observable,当是新开的WebSocket,注销掉当前的subscriber后,就没有其他subscriber了,这个新开的WebSocket就会关闭(share操作符作用).

最后,如有什么好的建议,可以联系我.

项目地址: https://github.com/dhhAndroid/RxWebSocket

如果对你有帮助,谢谢 star !

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